The generator function G for your Layer 2 Protocol’s Cyclic Redundancy Check is 1001. You have received the data D, 101000011. Answer the following questions with reference to G and D. You may assume that any error detection bits are found after the data bits. What is the largest burst error that we can detect with G?
Try an answer before revealing the guidance below.
Key Concepts
- Generator degree r
- Burst error
- CRC detection guarantee
Answer Approach
- Count the bits in G.
- Find r, the number of CRC bits, from the length of G.
- Recall the burst length a CRC with r check bits always detects.
Full Answer
Answer status: Draft answer (unofficial). Revision notes, not an official marking scheme.
G = 1001 has r + 1 = 4 bits, so r = 3. A CRC detects all burst errors of fewer than r + 1 bits, so the largest burst guaranteed to be detected is 3 bits.
r = len(G) − 1Detects all bursts of length ≤ rShortcuts: K concepts · A approach · F answer · R reviewed · B bookmark · ← / → previous / next